const DOCUMENT_TYPE_LABELS = {
  flight_itinerary: '机票/航班行程单',
  train_ticket: '火车/高铁票',
  hotel_invoice: '酒店住宿票据',
  taxi_receipt: '出租车/网约车票据',
  parking_toll_receipt: '停车/通行费票据',
  meal_receipt: '餐饮票据',
  office_invoice: '办公用品票据',
  meeting_invoice: '会议/会务票据',
  training_invoice: '培训票据',
  vat_invoice: '增值税发票',
  receipt: '一般收据/凭证',
  other: '其他单据'
}

function normalizeText(value) {
  return String(value || '').trim()
}

function uniqueTexts(values) {
  return [...new Set(values.map((item) => normalizeText(item)).filter(Boolean))]
}

function normalizeTone(value) {
  const tone = normalizeText(value).toLowerCase()
  if (tone === 'pass') return 'pass'
  if (tone === 'high') return 'high'
  if (tone === 'medium') return 'medium'
  if (tone === 'low') return 'low'
  return 'medium'
}

function resolveDocumentTypeLabel(value) {
  return DOCUMENT_TYPE_LABELS[normalizeText(value)] || DOCUMENT_TYPE_LABELS.other
}

function normalizeRuleBasis(value) {
  if (Array.isArray(value)) {
    return value.map((item) => normalizeText(item)).filter(Boolean)
  }

  const text = normalizeText(value)
  return text ? [text] : []
}

export function buildAttachmentInsightViewModel(metadata, item = {}) {
  if (!metadata) {
    return null
  }

  const documentInfo = metadata.document_info || {}
  const requirementCheck = metadata.requirement_check || null
  const analysis = metadata.analysis || null
  const documentTypeLabel =
    normalizeText(documentInfo.document_type_label) || resolveDocumentTypeLabel(documentInfo.document_type)
  const fields = Array.isArray(documentInfo.fields)
    ? documentInfo.fields
      .map((field) => ({
        label: normalizeText(field?.label),
        value: normalizeText(field?.value)
      }))
      .filter((field) => field.label && field.value)
      .map((field) => `${field.label}：${field.value}`)
    : []
  const ruleBasis = uniqueTexts([
    ...normalizeRuleBasis(analysis?.rule_basis || analysis?.ruleBasis),
    ...normalizeRuleBasis(requirementCheck?.rule_basis || requirementCheck?.ruleBasis),
    normalizeText(requirementCheck?.message),
    documentTypeLabel ? `票据识别依据：系统将附件识别为${documentTypeLabel}。` : '',
    normalizeText(item?.name) ? `费用项目依据：当前明细为${normalizeText(item.name)}。` : ''
  ])

  return {
    fileName: normalizeText(metadata.file_name || item.attachmentHint || item.invoiceId),
    mediaType: normalizeText(metadata.media_type),
    previewable: metadata.previewable !== false,
    documentTypeLabel,
    requirementLabel: requirementCheck
      ? (requirementCheck.matches ? '符合当前费用类型' : '不符合当前费用类型')
      : '待校验附件类型',
    requirementTone: requirementCheck
      ? (requirementCheck.matches ? 'pass' : 'high')
      : 'medium',
    message: normalizeText(requirementCheck?.message),
    fields: fields.slice(0, 8),
    ruleBasis,
    analysis: analysis
      ? {
        label: normalizeText(analysis.label) || 'AI提示',
        tone: normalizeTone(analysis.severity),
        headline: normalizeText(analysis.headline) || normalizeText(analysis.label) || 'AI提示',
        summary: normalizeText(analysis.summary),
        points: Array.isArray(analysis.points) ? analysis.points.map((point) => normalizeText(point)).filter(Boolean) : [],
        suggestion: normalizeText(analysis.suggestion)
      }
      : null
  }
}

function buildCardSuggestion(analysis, insight) {
  return (
    normalizeText(analysis?.suggestion)
    || normalizeText(insight?.message)
    || '请根据规则依据核对附件和费用明细，必要时补充说明、更换附件或调整费用项目。'
  )
}

function buildRiskCardFromPoint({ item, index, point, pointIndex, insight, analysis }) {
  const tone = normalizeTone(analysis?.severity)
  const label = normalizeText(analysis?.label) || (tone === 'high' ? '高风险' : '中风险')

  return {
    id: `${normalizeText(item?.id) || `expense-${index}`}-${pointIndex}`,
    tone,
    label,
    title: `第 ${index + 1} 条：${normalizeText(analysis?.headline) || normalizeText(item?.name) || '附件风险'}`,
    risk: normalizeText(point) || normalizeText(analysis?.summary) || '附件存在待核对风险。',
    summary: normalizeText(analysis?.summary),
    ruleBasis: insight?.ruleBasis?.length ? insight.ruleBasis : ['系统根据附件识别结果与费用项目规则进行比对。'],
    suggestion: buildCardSuggestion(analysis, insight)
  }
}

function parseReturnCount(flag) {
  const count = Number(flag?.return_count ?? flag?.returnCount ?? 0)
  return Number.isFinite(count) && count > 0 ? Math.floor(count) : 0
}

function resolveLatestManualReturnFlag(flags) {
  const manualReturnFlags = flags.filter(
    (flag) => flag && typeof flag === 'object' && normalizeText(flag.source) === 'manual_return'
  )
  if (!manualReturnFlags.length) {
    return null
  }

  return manualReturnFlags.reduce((latest, flag) => {
    const latestCount = parseReturnCount(latest)
    const nextCount = parseReturnCount(flag)
    if (nextCount !== latestCount) {
      return nextCount > latestCount ? flag : latest
    }

    const latestTime = Date.parse(normalizeText(latest?.created_at || latest?.createdAt))
    const nextTime = Date.parse(normalizeText(flag?.created_at || flag?.createdAt))
    if (Number.isFinite(nextTime) && (!Number.isFinite(latestTime) || nextTime >= latestTime)) {
      return flag
    }

    return latest
  }, manualReturnFlags[0])
}

function buildManualReturnRiskCard(flag) {
  if (!flag) {
    return null
  }

  const returnCount = parseReturnCount(flag)
  const stageReturnCount = Number(flag.stage_return_count ?? flag.stageReturnCount ?? 0)
  const returnStage = normalizeText(flag.return_stage || flag.returnStage || flag.previous_approval_stage)
  const riskPoints = Array.isArray(flag.risk_points || flag.riskPoints)
    ? (flag.risk_points || flag.riskPoints).map((item) => normalizeText(item)).filter(Boolean)
    : []
  const risk = normalizeText(flag.message || flag.reason || flag.summary) || '审批人退回该单据，请补充后重新提交。'
  const ruleBasis = uniqueTexts([
    returnCount ? `累计退回 ${returnCount} 次。` : '',
    returnStage ? `本次退回环节：${returnStage}。` : '',
    stageReturnCount > 0 ? `该环节累计退回 ${Math.floor(stageReturnCount)} 次。` : '',
    ...riskPoints.map((item) => `退回风险点：${item}。`)
  ])

  return {
    id: `manual-return-${returnCount || 'latest'}`,
    tone: 'medium',
    label: '退回原因',
    title: returnCount ? `第 ${returnCount} 次退回` : '审批退回',
    risk,
    summary: normalizeText(flag.reason),
    ruleBasis: ruleBasis.length ? ruleBasis : ['审批人已退回该单据。'],
    suggestion: '请按退回原因补充材料、修正明细或完善说明后重新提交。'
  }
}

export function buildAttachmentRiskCards({
  expenseItems = [],
  attachmentMetaByItemId = {},
  claimRiskFlags = []
} = {}) {
  const attachmentCards = expenseItems.flatMap((item, index) => {
    if (!item?.invoiceId) {
      return []
    }

    const metadata = attachmentMetaByItemId[item.id]
    const insight = buildAttachmentInsightViewModel(metadata, item)
    const analysis = metadata?.analysis
    const tone = normalizeTone(analysis?.severity)
    if (!analysis || !['medium', 'high'].includes(tone)) {
      return []
    }

    const points = Array.isArray(analysis.points) && analysis.points.length
      ? analysis.points
      : [analysis.summary || analysis.headline || analysis.label]

    return points
      .map((point, pointIndex) => buildRiskCardFromPoint({ item, index, point, pointIndex, insight, analysis }))
      .filter((card) => card.risk)
  })

  const normalizedClaimRiskFlags = Array.isArray(claimRiskFlags) ? claimRiskFlags : []
  const latestManualReturnCard = buildManualReturnRiskCard(resolveLatestManualReturnFlag(normalizedClaimRiskFlags))
  const claimCards = normalizedClaimRiskFlags
      .flatMap((flag, index) => {
        if (flag && typeof flag === 'object' && normalizeText(flag.source) === 'manual_return') {
          return []
        }

        if (!flag || typeof flag !== 'object') {
          const risk = normalizeText(flag)
          return risk
            ? [{
              id: `claim-risk-${index}`,
              tone: 'medium',
              label: '单据风险',
              title: '单据风险提示',
              risk,
              summary: '',
              ruleBasis: ['系统预审规则命中该风险提示。'],
              suggestion: '请结合业务背景补充说明或调整单据后再提交。'
            }]
            : []
        }

        const tone = normalizeTone(flag.severity)
        if (!['medium', 'high'].includes(tone)) {
          return []
        }

        const flagPoints = Array.isArray(flag.points)
          ? flag.points.map((point) => normalizeText(point)).filter(Boolean)
          : []
        const risks = flagPoints.length
          ? flagPoints
          : [normalizeText(flag.message || flag.reason || flag.summary)].filter(Boolean)
        const summary = normalizeText(flag.summary)
        const ruleBasis = uniqueTexts([
          ...normalizeRuleBasis(flag.rule_basis || flag.ruleBasis),
          summary ? `风险汇总：${summary}` : '',
          '系统预审规则命中该风险提示。'
        ])

        return risks.map((risk, pointIndex) => ({
          id: `claim-risk-${index}-${pointIndex}`,
          tone,
          label: normalizeText(flag.label) || (tone === 'high' ? '高风险' : '中风险'),
          title: normalizeText(flag.label) || '单据风险提示',
          risk,
          summary,
          ruleBasis,
          suggestion: normalizeText(flag.suggestion) || '请结合业务背景补充说明或调整单据后再提交。'
        }))
      })
      .filter(Boolean)
  if (latestManualReturnCard) {
    claimCards.unshift(latestManualReturnCard)
  }

  return [...attachmentCards, ...claimCards]
}

export function buildAiAdviceViewModel({ completionItems = [], riskCards = [] } = {}) {
  const normalizedCompletionItems = completionItems.map((item) => normalizeText(item)).filter(Boolean)
  const normalizedRiskCards = riskCards.filter(Boolean)
  const hasHighRisk = normalizedRiskCards.some((card) => card.tone === 'high')

  if (!normalizedCompletionItems.length && !normalizedRiskCards.length) {
    const items = [
      '点击右下角“提交审批”进入流程。',
      '提交前再核对一次合计金额与各条费用明细金额是否一致。',
      '如有特殊业务背景或例外情况，可在下方附加说明中补充。'
    ]

    return {
      tone: 'ready',
      badge: '可直接提交',
      summary: 'AI判断当前草稿已具备提交条件，可以直接发起审批。',
      items,
      riskCards: [],
      sections: [
        {
          kind: 'completion',
          title: '建议补充字段',
          items
        }
      ]
    }
  }

  const sections = []
  if (normalizedCompletionItems.length) {
    sections.push({
      kind: 'completion',
      title: '建议补充字段',
      items: normalizedCompletionItems
    })
  }
  if (normalizedRiskCards.length) {
    sections.push({
      kind: 'risk',
      title: '已知存在风险',
      items: normalizedRiskCards
    })
  }

  return {
    tone: hasHighRisk ? 'warning' : 'pending',
    badge: hasHighRisk ? '优先整改' : '待核对',
    summary: normalizedRiskCards.length
      ? `AI已整理出 ${normalizedRiskCards.length} 个风险点，请逐项核对规则依据和修改建议。`
      : '建议先补齐必填信息，完成后即可提交审批。',
    items: normalizedCompletionItems,
    riskCards: normalizedRiskCards,
    sections
  }
}